characterization of different dopants in tio2 structure by pulsed laser deposition

Characterization of different dopants in TiO2 Structure by

Pulsed Laser Deposition

Supervised by

Prof.Dr. Adawiya J.Haider Prof.Dr. Raad M.S.Al-Haddad

UNIVERSITY OF TECHNOLOGY

A thesis submitted By

Khaled Z.Yahya

يم� ح� الر� من� ح� الر� الل�ه� م� ب�س�

ت�ن�ا ع�ل�م� ا �م إ�ال� ل�ن�ا �ل�م ع� �ال �ان�ك �ب�ح س' ال'وا� �ق

�أ�نت ��ن�ك ك�يم' إ �ال�ح ال�ع�ل�يم'

ال�ع�ظ�يم' الل�ه' �د�ق � ص

{٣٢البقرة }

PLD: Pulsed Laser Deposition The interaction of the laser beam with

the target resulting in evaporation of the surface layers.

The interaction of the laser beam with the evaporation materials causing the formation ofisothermal expanding plasma.

The expansion of the laser induced plasma with a rapid transfer of thermal energy of the species in plasma into kinetic energy.

Thin film growth.

Rotating target

Laser Pulsed

Substrate heater

Ejected Plume

Deposited

film

Why TiO2?

Titanium dioxide (TiO2) is a wide band gap (3.2) eV for anatase and 3 eV for rutile .

Titanium dioxide have high refractive index - up to 2.7 (at wavelength of 600nm)

Titanium dioxide good chemical resistance and high chemical stability.Titanium dioxide good sensitivity to poison gases. Titanium dioxide good photocatalysts.

3

TiO2 structure

Anatase Rutile Brockets

TiO2 gas sensor

• TiO2 based sensor are predominant solid-state gas sensors for domestic, commercial and industrial application.

• •Low cost• •Easy production • •Rigid construction• •Compact size• •Simple measuring electronics

Aim of the work The aim of this work is to reveal specific properties of TiO2

nanostructure prepared by pulsed laser deposition technique TiO2 samples have been prepared at different dopant noble metal such as (Pd ,Pt, Ni, Ag,…) The main objective of this work are :

• 1. Characteristics of structural , microstructural and photoluminescence properties of thin films .

• 2. Studying the sensitivity and selectivity of these films doped with different noble metal deposited by PLD to CO gas.

6

Experimental Work

7

Prepared TiO2

Picture for TiO2 ceramic

Pulsed Laser Deposition (PLD)

Plasma plume

TiO2 thin film

Characterization Measurements of prepare films

Films thickness measurement

XRD Study

TCO film Morphology SEM ,AFM

Optical properties

photoluminescence properties

Gas sensor measurement

a)SEM b)AFM c)PL d)Gas sensing

c d

a ba b

Results

7

10

•Substrate Temperatures effect (Ts )

c

b

a

2θ (degree)

A :anatase

Figure (1) XRD spectra of TiO2/glass at different temperature a) 200ºC b) 300ºC, c)400ºC

Intensity (a.u)

laser fluence 0.8 J/cm2 oxygen pressure 5 *10-1 Torr

TiO2 /Si

FWHM and Main grain size

0

10

20

30

40

50

250 300 350 400 450 500 550

Temperature °C

Mai

n gr

ain

size

(nm

)

0.420.430.440.450.460.470.480.490.5

0.51

250 300 350 400 450 500 550

Temperature °C

FWH

M °

a b

Figure (3) TiO2 A(101) thin films grown on Si (111) at different substrate temperature for (a) main grain size (b)FWHM

Oxygen pressure effect

Fig (4) XRD patterns of TiO2 films grown on Siat various oxygen pressures a) 5×10-2 Torr b) 5×10-1 Torr c) 10 Torr

Intensity

(a.u)

2θ (degree)

Laser Fluence effect

Fig (5) XRD patterns of TiO2 films grown on Si

at various laser fluence a) 1.2 b) 0.8 c) 1.8 J/cm2

Doping effect of noble metal (Ag, Pt, Pd and Ni).

X - ray Florescence

Fig (7) X-ray florescence pattern for a) TiO2 pure b) TiO2 3% Ag c) TiO2 3% Pt d) TiO2 3% Pd e) TiO2 3% Ni .

a

b

SEM Substrate Temperatures effect (Ts )

Figure (8) SEM image of the TiO2/Si thin films deposited at various temperature of

a) 300°C, b) 400°C, c) 500°C, and laser fluence 1.2 J/cm2 ,O2 pressure=

10-1 mbar

Oxygen pressure effect

c

ba

Figure (9) SEM image of the TiO2/Si thin films deposited at various oxygen pressure a ) 5×10-2 mbar, b) 5×10-1 mbar and c) 10 mbar at

substrate temperature 500 °C and laser fluence 1.2 J/cm2


a

c

b

d

Figure (10) SEM image of the TiO2/Si thin films doping 3% with different noble metal a) Ag b) Pt c) Pd and d) Ni

SEM of plane grain size (nm) X-ray of plane grain size (nm) sample

29 31 TiO2 Pure 300°C

35 36.3 TiO2 Pure 400°C

40 41.28 TiO2 Pure 500°C

Table (1). The grain size of the TiO2 films

SEM of plane grain size (nm) X-ray of plane grain size (nm) O2 Pressure (mbar) sample

33 34 5×10-2 TiO2/Si

39 41 5×10-1 TiO2/Si

34 36 10 TiO2/Si

SEM of plane grain size (nm) X-ray of plane grain size (nm)

Dopants atom Radii (pm)

sample

15 15.7 126 TiO2 % 3 Ag

11 11.6 130 TiO2 % 3 Pt

20 21.5 72 TiO2 % Pd 3

18 19 69 TiO2 % Ni 3

Atomic Force Microscopy (AFM)

Substrate Temperatures effect (TS)

Figure (11) AFM image of the TiO2/Si thin films deposited at various substrate temperature ofa) 300°C, b) 400°C, c) 500°C, and laser fluence 1.2 J/cm2 ,O2 pressure=10-1 mbar

Oxygen Pressure effect

Figure (12) AFM image of the TiO2/Si thin

films deposited at various oxygen pressure a ) 5×10-2 mbar, b ) 5×10-1 mbar and c) 10

mbar at substrate temperature 500 °Cand laser fluence 1.2 J/cm2

doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)

b

c

d

a

Figure (13) AFM image of the TiO2/Si thin films doping 3% with different noble metal

a) Ag b) Pt c) Pd and d) Ni substrate temperature 500 °C

and laser fluence 1.2 J/cm2 with O2

pressure=10-1 mbar.

Table (2). The RMS and roughness of TiO2 films from AFM

RMS roughness(nm) AFM of plane grain size (nm) X-ray of plane grain size(nm) sample

2.1 30 31 TiO2 Pure 300°C

4 34.4 36.3 TiO2 Pure 400°C11.2 42 41.28 TiO2 Pure 500°C

RMS roughness

AFM of plane grain size (nm) X-ray of plane grain size (nm) (O2) Pressure mbar sample

4 (nm) 32 34 5×10-2 TiO2/Si

6 nm 40 41 5×10-1 TiO2/Si

16.7nm 33 36 10 TiO2/Si

RMS roughness AFM of plane grain size (nm) X-ray of plane grain size (nm) sample

26 nm 16 15.7 TiO2 :3% Ag

28 nm 12.4 11.6 TiO2 :3% Pt

23 nm 23 21.5 TiO2 :3% Pd

24 nm 20.5 19 TiO2 :3% Ni

Optical Properties Transmission

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000

Wave length (nm)

T (%

)

TiO2 400 C

TiO2 300 C

TiO2 200 C


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000

Wave length (nm)

T

(%)

10 mbar

10 -2 mbar

10 -1 mbar

Oxygen Pressure effect

0

10

20

30

40

50

60

70

80

90

0 200 400 600 800 1000

Wave length (nm)

T (%

)

0.8 J/cm2

1.8 J/cm2

1.2 J/cm2

Laser Fluence effect

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000

Wave length (nm)

Tra

nsm

tan

ce %

TiO2 :3% Ag

TiO2 :3% Pd

TiO2 :3%Ni

TiO2 :3% Pt

TiO2 Pure


Optical Energy Gap Eg°

Substrate Temperatures effect (Ts )


direct Eg


Indirect Eg

Table (3) Physical and optical measurements for pure and doped TiO2 films

Optical energy gab E°g (eV)(indirect)

Optical energy gab E°g (eV)(direct)

Samples

3.03 3.4 TiO2 Pure at 200 °C

3.1 3.5 TiO2 Pure at 300 °C

3.2 3.6 TiO2 Pure at 400 °C

3.12 3.42 TiO2:1%Ag at 200 °C

3.20 3.5 TiO2 :2%Ag at 200 °C

3.28 3.67 TiO2 :3%Ag at 200 °C

3.11 3.41 TiO2 :1%Pt at 200 °C

3.19 3.52 TiO2 :2%Pt at 200 °C

3.25 3.58 TiO2 :3%Pt at 200 °C

2.93 3.42 TiO2:1%Pd at 200 °C

2.9 3.37 TiO2 :2%Pd at 200 °C

2.88 3.32 TiO2 :3%Pd at 200 °C

2.94 3.42 TiO2:1%Ni at 200 °C

2.9 3.38 TiO2 :2%Ni at 200 °C

2.8 3.35 TiO2 :3%Ni at 200 °C

Refractive index (n)

0

0.5

1

1.5

2

2.5

3

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

hv (eV)

Refra

ctiv

e in

dex

(n)

TiO2 400 C

TiO2 300 C

TiO2 200 C



0

0.5

1

1.5

2

2.5

3

3.5

0 1 2 3 4 5

hv (eV)

Refr

acti

ve in

dex (

n) TiO2 Pure

TiO2 :1%Ag

TiO2 :2% Ag

TiO2 :3%Ag

0

0.5

1

1.5

2

2.5

3

3.5

0 1 2 3 4 5

hv (eV)

Refr

acti

ve in

dex (

n) TiO2 Pure

TiO2 :1% Pt

TiO2 :2% Pt

TiO2 :3%Pt

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

hv (eV)

Ref

ract

ive

inde

x (n

)

TiO2 Pure

TiO2 :3% Pd

TiO2 :2% Pd

TiO2 :1% Pd

0

0.5

1

1.5

2

2.5

3

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

hv (eV)

Ref

ract

ive

inde

x (n

)

TiO2 Pure

TiO2 :3% Ni

TiO2 :2%Ni

TiO2 :1% Ni

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5

hv (eV)

extin

ctio

n co

effic

ient

(K)

TiO2 :3% Ag

TiO2 :2% Ag

TiO2 :1% Ag

TiO2 Pure

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5

hv (eV)ex

tinct

ion

coef

ficie

nt (K

)

TiO2 :3%Pt

TiO2 :2%Pt

TiO2 :1%Pt

TiO2 pure

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5

hv (eV)

extin

ctio

n co

effic

ient

(K)

TiO2 Pure

TiO2 :1%Pd

TiO2 :2%Pd

TiO2 :3%Pd

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5

hv (eV)

extin

ctio

n co

effic

ient

(K)

TiO2 Pure

TiO2 :1%Ni

TiO2 :2%Ni

TiO2 :3%Ni

Extinction Coefficient

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5

hv (eV)

exti

nct

ion

co

effi

cien

t (K

)

TiO2 200 C

TiO2 300 C

TiO2 400 C



Photoluminescence (PL) Substrate Temperature effect (Ts)

c

a b

Figure (23) Photoluminescence spectrum of pure TiO2/glass thin films deposited at various substrate temperature of

a) 300°C, b) 350 °C, c) 400°C, and laser fluence 1.2 J/cm2 ,O2 pressure=10-1 mbar

The doping effect of noble metals (Ag ,Pt ,Pd ,and Ni)

a b

c d

Figure (24) Photoluminescence spectrum of the TiO2/glass thin films doping 3% with different noble metal a) Ag b) Pt c) Pd

and d) Ni ,at substrate temperature 400 °C

and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar.

Table (4) Energy values and Intensity of PL Peaks

Samples Energy of PeakA (eV)

Intensity (a.u) Energy of Peak B (eV) Intensity (a.u) Optical energy gap (eV) E°

g

TiO2 at 300°C 3.06 840 2.39 365 3.03

TiO2 at 350°C 3.12 900 2.4 390 3.1

TiO2 at 400°C 3.22 1000 2.43 415 3.2

TiO2 :3% Ag at

400°C

3.24 280 2.45 150 3.28

TiO2 :3% Pt at

400°C

3.25 540 2.5 380 3.25

TiO2 :3% Pd at

400°C

2.93 810 2.33 350 2.88

TiO2 :3% Ni at

400°C

2.85 820 2.3 400 2.8

Sensing properties

Room Temperature

0

0.02

0.04

0.06

0.08

0.1

0.12

0 200 400 600 800 1000

Time (sec)

Sen

seti

vit

y

TiO2 Pure

TiO2:3%Pt

TiO2:3%Ag

TiO2:3%Pd

TiO2:3%Ni

Figure (24) Sensitivity for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at Room temperature and

laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar

Operation time Effect on sensing properties

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 100 200 300 400 500 600 700 800 900

Time (sec)

Sen

sit

ivit

y

TiO2 Pure

TiO2 :1% Ag

TiO2 :2% Ag

TiO2 :3% Ag

0

0.5

1

1.5

2

2.5

3

3.5

0 100 200 300 400 500 600 700 800 900

Time (sec)

Sen

sit

ivit

y

TiO2 Pure

TiO2 :1% Pt

TiO2 :2% Pt

TiO2 :3% Pt

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 100 200 300 400 500 600 700 800 900

Time (sec)

Sen

sit

ivit

y

TiO2 Pure

TiO2 :1% Pd

TiO2 :2% Pd

TiO2 :3% Pd

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 100 200 300 400 500 600 700 800 900

Time (sec)S

en

sit

ivit

y

TiO2 Pure

TiO2 :1% Ni

TiO2 :2%Ni

TiO2 :3% Ni

a b

dc

Figure (25) Sensitivity for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at operation temperature 250 °C and

laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar

Operation time Effect on resistance properties

0

2

4

6

8

10

12

0 200 400 600 800 1000

Time (sec)

Resis

tan

ce (oh

m)

*10

9

TiO2 Pure

TiO2 :1% Ag

TiO2 :2% Ag

TiO2 :3% Ag

0

2

4

6

8

10

12

0 200 400 600 800 1000

Time (sec)

Resis

tan

ce (oh

m)

*10

9

TiO2 Pure

TiO2 :1% Pt

TiO2 :2% Pt

TiO2 :3% Pt

0

2

4

6

8

10

12

0 200 400 600 800 1000

Time (sec)

Resis

tan

ce (oh

m)

*10

9

TiO2 Pure

TiO2 :1% Pd

TiO2 :2% Pd

TiO2 :3% Pd

0

2

4

6

8

10

12

0 200 400 600 800 1000

Time (sec)

Resis

tan

ce (o

hm

) *1

09

TiO2 Pure

TiO2 :1% Ni

TiO2 :2% Ni

TiO2 :3% Ni

Figure (26) resistance for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at operation

temperature 250 ° C and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar

a b

c d

Operation time Effect on current properties

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000

Time (Sec)

cu

rren

t (n

A)

TiO2 pure

TiO2 1% Ag

TiO2 2% Ag

TiO2 3% Ag

0

1

2

3

4

5

6

7

8

9

10

0 200 400 600 800 1000

Time (Sec)

cu

rren

t (n

A)

TiO2 pure

TiO2 1%Pt

TiO2 2%Pt

TiO2 3%Pt

0

1

2

3

4

5

6

7

0 200 400 600 800 1000

Time (Sec)

cu

rren

t (n

A)

TiO2 pure

TiO2 1% Pd

TiO2 2% Pd

TiO2 3%Pd

0

1

2

3

4

5

6

0 200 400 600 800 1000

Time (Sec)

cu

rren

t (n

A)

TiO2 pure

TiO2 1% Ni

TiO2 2% Ni

TiO2 3% Ni

a

dc

b

Figure (27) current for TiO2 /glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at

operation temperature 250 ° C and laser fluence 1.2 J/cm2 with O2

pressure=10-1 mbar

Operation temperature Effect on sensing properties

0

0.5

1

1.5

2

2.5

3

0 50 100 150 200 250 300 350 400 450

T(C)

Sens

itivi

ty

TiO2 Pure

TiO2 :2% Ag

TiO2 :3% Ag

TiO2 :1% Ag

0

0.5

1

1.5

2

2.5

3

3.5

4

0 50 100 150 200 250 300 350 400 450

T(C)

Sens

itivi

ty

TiO2 Pure

TiO2 :2% Pt

TiO2 :3% Pt

TiO2 :1% Pt

0

0.5

1

1.5

2

2.5

0 50 100 150 200 250 300 350 400 450

T(C)

Sens

itivi

ty

TiO2 Pure

TiO2 :2% Pd

TiO2 :3% Pd

TiO2 :1% Pd

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 50 100 150 200 250 300 350 400 450

T(C)

Sens

itivi

ty

TiO2 Pure

TiO2 :2% Ni

TiO2 :3%Ni

TiO2 :1% Ni

Figure (28) Sensitivity for TiO2/glass pure and doping with 1% ,2% and 3% (Ag ,Pt ,Pd ,and Ni) films for CO gas at different operation temperature and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar

a b

c d

Sensitivity of TiO2 /Si

0

5

10

15

20

25

0 100 200 300 400 500

T (C)

Sen

siti

vity

TiO2 Pure

TiO2:3% NI

TiO2:3% Pd

TiO2:3% Ag

TiO2:3%Pt

Figure (29) Sensitivity for TiO2/Si pure and doping with 3% (Ag ,Pt ,Pd ,and Ni) films for

CO gas at different operation temperature at laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar

Table (5) Sensitivity values of TiO2 pure and doping with different

noble metal concentration at operation temperature T= 250 °C.

Samples Sensitivity

TiO2 pure/glass 0.5

TiO2 :1% Ag /glass 1.7

TiO2 :2% Ag/glass 2.3

TiO2 :3% Ag/glass 2.7

TiO2 :1% Pt/glass 2.2

TiO2 :2% Pt/glass 3

TiO2 :3% Pt/glass 3.3

TiO2 :1% Pd/glass 1.5



TiO2 :1% Ni/glass 0.85



TiO2 pure/Si 7.5

TiO2 :3% Ag/ Si 17

TiO2 :3% Pt/ Si 23

TiO2 :3% Pd/ Si 15

TiO2 :3% Ni/ Si 12.5

The results in this work agreement with other results as shown in table below :

References Metal dopantTiO2Selectivity Sensitivity

[46] - CO 2

[136] - CO 4

[45] - Ethanol and methanol vapor 5

[30] Pt CO 20

[39] Pd CO , H24 , 2.5

[81] Nb CO 14

[this work] Pt CO 23

Ag CO 17

Pd CO 14

Ni CO 11

- CO 7.5

ConclusionPure TiO2 showed poor response to CO gas.3 % wt Ag ,Pt ,Pd and Ni doped TiO2 thin film was the

most sensitive element to CO gas .The optimum operating temperature for CO gas sensing was (250) °C . Ag ,Pt ,Pd and Ni doped TiO2 thin film would be

suitable for fabricating the CO gas sensors.The sensor TiO2 doping with Pt showed good

selectivity to CO gas. TiO2 deposited on silicon has sensitivity to CO gas

higher than TiO2 deposited on glass

Future Work• 1- Studying (TiO2) films as antireflection

coating on (p-n) junction solar cells and as a photocatalyst .

• 2- Using a mixing of background gas N2

+ O2 with high vacuum to enhancement the quality of the films.

• 3- Studying (TiO2) films as a gas sensor for NO2 and H2 gas .

•

Paper accepted

1- “Structural and optical properties of TiO 2 photocatalyst thin

film produced by PLD”.Iraqi Journal science 3rd Scientific conference Baghdad University. 2- "Investigation of structural and Morphology properties of Nanocrystalline thin films prepared by PLD ".Journal of the collage education in the 6th conference on physics .

Paper submitted 3-" Structure and Morphology properties of nanocrystalline noble metal doped films for gas sensing properties "-2nd conference of nano technology and advance material and their application .4-" Nanostructure dopants TiO2 films for gas sensing".

Iraqi Journal of applied physics .

UNIVERSITY OF TECHNOLOGY

Thank you

characterization of different dopants in tio2 structure by pulsed laser deposition

Technology

tio2 pure b tio2

ag c tio2

tio2 gas sensor tio2

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torr c

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pt d tio2